preact-custom-element/src/internal.d.ts

Wrap your component up as a custom element

import { h, AnyComponent } from 'preact';

export type PreactCustomElement = HTMLElement & {
	_root: ShadowRoot | HTMLElement;
	_vdomComponent: AnyComponent;
	_vdom: ReturnType<typeof h> | null;
	_props: Record<string, unknown>;
};